The present invention relates to water-heating boilers.
The present invention, more particularly, relates to water-heating boilers of the tube-shell shape.
Conventional water-heating boilers of the tube-shell type, commonly include a relatively large diameter combustion tube, and a series of smaller heat transfer tubes, extending between two parallel upright tube sheets. In these conventional embodiments, the various tubes are horizontally arranged, so that the hot combustion gases flow horizontally through the various heat transfer tubes. Typically, a cylindrical shell encircles the tubes to form a water chamber. Heat contained in the hot gases, is conducted through the heat transfer tube walls into the surrounding water.